In commercial operations the closures of cans are attached to the cylindrical bodies of the cans by a crimping operation wherein the ends of the cylindrical bodies are forced in sealing relation against an elastomeric gasket which has been deposited along the rims of the end closures of the cans. To accomplish this a ring of elastomer (which is dissolved in a solvent) is placed along the periphery of one side of the can closure, namely, what will become the infacing side of the can closure. The elastomer is dried to eliminate solvent. The rim of the cylindrical can body is brought up against the closure and, under suitable temperature and pressure conditions, the closure is double seemed to the can body. The ring of elastomeric sealant which remains after the solvent has been driven off provides the seal between the can body and the closure. Water suspended elastomers can be utilized in which case the problem of getting rid of VOCs is either greatly reduced or eliminated. However, it is often desirable to utilize organic solvents, for example toluene or cyclohexane, since these allow very uniform deposition of sometimes different, and for some purposes better, elastomers and since such solvents are more readily vaporized and driven away from the can closures by heat. However, this introduces a problem of getting rid of the resulting volatilized solvents, i.e., the VOCs, in an environmentally acceptable manner.
In accordance with prior art procedures the volatile organic solvents which are volatilized during the drying of can closures have been allowed to escape into the air of the workplace and have then been absorbed or otherwise disposed of by cycling the workplace air, often the entire volume within a large factory, through an appropriate VOC removing stage. Since the factories have generally not been sealed environments this has led to a significant escape of VOCs into the surrounding atmosphere. As a result, there has been increasing movement towards legislation which would ban the use of organic solvents in canmaking operations. But, as pointed out above the use of organic solvents can be very advantageous. Accordingly, it would be highly desirable if a procedure could be developed for the canmaking industry which would allow volatile organic solvents to be utilized but would at the same time effectively protect not only the external environment, but also the environment within a factory wherein workers can be exposed to breathing such potentially hazardous chemicals.
The catalytic oxidation of VOCs to remove them from the atmosphere is a well known process. However, such systems have not been available for addressing the VOC problems of the canmaking industry. Indeed, it does not seem that any industry has provided heated dryers for driving off VOCs which have utilized catalytic oxidation units to eliminate the VOCs volatilized in the dryers without their being allowed to escape into the atmosphere. Thus, such systems have generally been applied only to abate the VOCs which escape from various apparatus into the atmosphere. That is, such catalytic oxidation systems have not been, generally, applied to closed drying systems. Representative of such systems are those shown in Guyffon, U.S. Pat. No. 3,710,756, issued Jan. 16, 1973 which shows gathering solvent vapor that evaporates from enamel into the surrounding atmosphere (an oven is provided to cure the enamel after the solvent has been volatilized), which enamel is used to coat wires and catalytically combusting it and Bergland, U.S. Pat. No. 4,343,096 and Henricks, U.S. Pat. No. 4,475,294 which control the emission of solvent by oxidizing the solvent. Also, of interest are Betz, U.S. Pat. Nos. 4,702,892 and 4,867,949 which disclose catalytic oxidation devices.
The present invention is directed to overcoming one or more of the problems as set forth above.